1. Technical Field
The present invention relates to a catalytic composition for oxychiorination. More specifically, this invention relates to a catalytic composition for oxychlorination which is excellent in such characteristics as fluidity, the capability of suppressing deterioration in fluidity, and attrition resistance and also is excellent in such characteristics as activity, selectivity for 1,2-dichlorethane (sometimes referred to as EDC hereinafter), and the capability of suppressing combustion of ethylene.
2. Background Technology
For chlorination of aliphatic hydrocarbons by oxychlorination, there has generally been used a catalyst in which a metal salt is carried on a porous carrier such as alumina, silica alumina, and clay. Especially, there has been used in the industrial field, for a long time, a catalyst for a fluidized bed in which cupric chloride is carried on an alumina carrier by impregnation, when the EDC is manufactured by means of oxychlorination of ethylene. In this catalyst, the copper which is an active component moves or sublimes to cause deterioration of the activity or deterioration of the fluidity, and as a result, temperature distribution in the catalyst layer becomes heterogeneous and combustion of ethylene rapidly proceeds in a heated area, which disadvantageously leads to deterioration of the selectivity for EDC or deterioration of the yield. To suppress movement or sublimation of copper, and furthermore to improve the selectivity for EDC, such a material as an alkali metal, an alkali earth metal, or a rare earth metal is added to the catalyst.
On the other hand, there has been known the catalyst obtained by simultaneously precipitating a carrier component and an active component (this method is sometimes referred to as “co-precipitation method” hereinafter) and spray-drying the precipitates (Refer to Patent document 1). Furthermore, there has been known the catalyst prepared by the coprecipitation method and having such a material as an alkali metal, an alkali earth metal, or a rare earth metal on the catalyst (Refer to Patent documents 2 to 4).
The present inventors disclosed that the catalyst, which is prepared by using a pseudo boehmite alumina slurry previously prepared as an alumina source, adding an active component such as copper and an auxiliary catalytic component such as an alkali, an alkali earth metal, or a rare earth metal to the boehmite alumina slurry, and spray-drying the components, little shows lowering of the fluidity and also shows high activity and high selectivity (Refer to Patent documents 5 and 6).
In the fluidized bed oxychlorination method based on the conventional technology, because the activity and selectivity of the catalyst are apt to lower or the catalyst is apt to be scattered as time goes by, new catalyst is added while a portion of old catalyst is being taken away. Furthermore, the activity and the selectivity of the conventional catalysts using alumina as a carrier are relatively high in the initial state, but the performances are not preserved for a long time, and therefore in a case of a catalyst using silica alumina as a carrier, not only the initial activity and selectivity are insufficient, but also combustion of ethylene rapidly proceeds, which leads to deterioration of the selectivity for EDC with the yield lowered.
For the reasons as described above, it is strongly required to suppress combustion of ethylene and also to suppress deterioration of the selectively for EDC and lowering of the yield.
Patent document 1: JP S45-39616 B
Patent document 2: JP H11-90232 A
Patent document 3: JP H11-90233 A
Patent document 4: JP H11-90234 A
Patent document 5: JP 2005-000730 A
Patent document 6: JP 2005-000731 A